Swivel chuck

ABSTRACT

A swivel chuck in which a body is rotatable about a first axis and has two bell cranks pivoted thereto about the second axes perpendicular to the first, shorter arms of the bell cranks being acted upon by a hydraulic member movable parallel to the first axis, to pivot the bell cranks, the longer arms of which carry at their free ends jaws which are rotatable about a third axis perpendicular to the first and second axes. Links pivoted to the jaws and the body form a parallelogram linkage to maintain the orientation of the jaws. Three pistons, movable in cylinders carried by the longer arms, have shoes connected thereto which abut rollers, arranged in pairs in grooves in an actuating member connected to each jaw, the rollers of a pair being at 180* to one another, while the rollers in adjacent grooves are at 60* to one another, with respect to the third axis. Movement of a selected one of the pistons will thus rotate the actuating member and associated jaw.

United States Patent [191 Zeidler [54] SWIVEL CHUCK Willy Zeidler, 8729Hofheim, Germany HEWA-HESSISCHER Werkzeugund Apparatebau Alfred Vogler,Pfaffenwiesbach, Germ any Filed: Aug. 4, 1971 Appl. No.2 169,023

lnventor:

Assignee:

[30] Foreign Application Priority Data Aug. 4, 1970 Germany ..P 20 38574.4

US. Cl. ..279/4, 279/5, 279/109 Int. Cl. ....B23b 31/18, B23b 31/34,B23b 31/30 Field of Search ..279/4, 5, 106, 107,

[5 6] References Cited FOREIGN PATENTS OR APPLICATIONS 328,776 11/1920Germany ..279/5 51 May 15, 1973 Primary ExaminerFrancis S. HusarAttorney- Louis E. Marn et al.

[57] ABSTRACT A swivel chuck in which a body is rotatable about a firstaxis and has two bell cranks pivoted thereto about the second axesperpendicular to the first, shorter arms of the bell cranks being actedupon by a hydraulic member movable parallel to the first axis, to pivotthe bell cranks, the longer arms of which carry at their free ends jawswhich are rotatable about a third axis perpendicular to the first andsecond axes. Links pivoted to the jaws and the body form a parallelogramlinkage to maintain the orientation of the jaws. Three pistons, movablein cylinders carried by the longer arms, have shoes connected theretowhich abut rollers, arranged in pairs in grooves in an actuating memberconnected to each jaw, the rollers of a pair being at 180 to oneanother, while the rollers in adjacent grooves are at 60 to one another,with respect to the third axis. Movement of a selected one of thepistons will thus rotate the actuating member and associated jaw.

10 Claims, 13 Drawing Figures The present invention relates to a swivelchuck, such as may be used for turning machines.

One type of swivel chuck has at least two clamping jaws adapted formutual movement perpendicularly to the axis of rotation of the chuck andat the same time rotatable by an actuating mechanism, through predetermined angles, about a pivot axis perpendicular to the axis ofrotation of the chuck, pressurized pistons being actuatableperpendicularly to the pivot axis of the clamping jaws and acting onactuation surfaces.

According to the invention there is provided a swivel chuck comprising abody adapted to be rotated about a first axis, two arms each pivoted tosaid body about a second axis perpendicular to the first axis, each armcarrying a jaw at a location spaced from its second axis, each said jawbeing rotatable with respect to its associated arm about a third axis,perpendicular to the first and second axes, a cylinder carried by eacharm and having at least two pistons reciprocable therein, and anactuating member rotatable with each jaw, each actuating member havingat least two sets of actuation surfaces, angularly offset with respectto one another about said third axis and positioned to be acted upon bysaid pistons to cause rotation of said members and thus of said jaws.

With such a construction, it is possible to index the clamping jawsthrough very small divisional angles. The jaws can be pivoted in bothsenses of rotation and the chuck can combine great precision of indexingwith less exact production than is the case for known swivel chucks.

The pistons have piston rods at the free ends of which piston shoes mayextend perpendicularly to the third axis and engage the actuationsurfaces, to rotate the actuating member and associated jaw.

Suitably the respective actuation surfaces of the sets are mutuallyoffset by the predetermined divisional angles. Thus upon indexing of theclamping jaws one of the sets of actuation surfaces arranged on theactuating member will always come into operative engagement with theassociated piston. Since a considerably greater amount of space isavailable because of the axial juxtaposition than is the case in knownswivel chucks, the actuating member can also be turned by very smallangles of division.

Preferably the actuation surfaces on the actuating member are formed inaxially juxtaposed annular grooves and in a particularly preferredembodiment the actuation surfaces are in the form of rollers disposed inthe annular grooves and rotatable about axes parallel to the third axis,two of these rollers always cooperating to form an actuation surface. Inthis embodiment there is virtually no sliding friction between thepiston shoes and the actuation surfaces so that rotation over even thesmallest divisional angle becomes practicable. By virtue of the absenceof sliding friction the wear on the actuation surfaces and on thecorresponding surfaces of the piston shoes is also reduced to a minimumso that the life of the swivel chuck during which the necessaryprecision is to be maintained is very considerably prolonged.

The rollers of the individual actuation surfaces are suitably arrangedat equal angular distances. But it is also at any time possible toselect unequal angles since it is merely necessaryfor the sum of theangular offsets of all actuation surfaces to enable a full revolution ofthe actuating member. The rollers of one set of actuation surfaces mayhave identical diameters. But angular differences which normally do notlie in the scope of divisional pivoting can be taken into considerationby differing roller diameters.

In a specially advantageous development of the concept of the inventionit is envisaged for the rollers in the actuating member, or for theactuating member with the rollers as a whole, to be exchangeable. Thusit is possible to set partial pivotal movements for the most diverseangles with one and the same swivel chuck, according to therequirements.

According to another aspect of the invention, there is provided a swivelchuck comprising a body adapted to be rotated about a first axis, twobell cranks each pivoted to said body about a second axis perpendicularto said first axis, a jaw carried by a first arm of each bell crank, soas to be rotated about a third axis perpendicular to the first andsecond axes, means to rotate the jaws about said third axis, the secondarm of the bell crank being connected to means acting parallel to thefirst axis to pivot the bell cranks about said second axis or axes andwherein a link is associated with each bell crank, each link beingpivoted to the body and to the associated jaw, the effective length ofsaid link being equal to the distance between the third axis and thesecond axis of that bell crank, to provide a parallelogram linkage tosupport said jaw for a constant angular position during pivoting of thebell crank.

The present invention will be more readily understood from the followingdescription of an embodiment, reference being made to the accompanyingdrawings, in which:

FIG. 1 shows a part-sectional side elevation of one embodiment of swivelchuck according to the invention;

FIG. 2 shows a view in the direction of the arrow A and a section alongline B-C of FIG. 1;

FIGS. 3 to 8 are diagrammatic representations of the switching mechanismused in the swivel chuck of the invention, in various switchedpositions;

FIGS. 9 and 10 show a representation corresponding to FIGS. 3 to 8, withactuation rollers of different diameters;

FIGS. 11 to 13 show a diagrammatic illustration of the kinematics of themost essential swivel chuck elements in transition from the opened tothe closed position of the clamping jaws.

As shown in FIG. 1, the swivel chuck comprises a chuck body 1 revolvingabout a first axis 2 of a turning machine (not shown) bell cranks 3pivoted to the chuck body 1 and movable in opposite directions aboutsecond axes 4 perpendicular to axis 2 and clamping jaws 5 secured to thefree ends of the bell cranks 3 so as to be rotatable about a third axisperpendicular to -the axis of rotation 2, and to the axes of pivots 4.

A piston 7 pressurized by a pressure medium is reciprocable coaxially ofthe axis 2 in a cylinder 6 in the chuck body 1. The front end of thepiston is connected by guide shackles 8 to those angled lever arms 9 ofthe bell cranks 3 which point towards the axis 2. The angled lever arms9 pointing towards the axis of rotation 2 are shorter than thesubstantially axially extending lever arms 10 of the bell cranks 3, in aratio of about 1:2. Accordingly, an axial displacement of the piston 7in the cylinder 6 results in an opening or closing path of twofoldtransmission ratio for the clamping jaws 5. The piston 7 is adapted tobe pressurized by pressure media via bores 11 and 12.

The clamping jaws are mounted via journal pins 13 at the free ends ofthe longer arms of the bell cranks 3, so as to be pivotable about anaxis parallel to the second axes. The jaws 5 are also rotatable, asindicated by the curvilinear arrows, about an axis perpendicular to boththe first and second axes. Radially outward of the pins 13 on theclamping jaws 5 there are located further pins parallel thereto, whichpins 14 define an axis which, together with the axis defined by the pins13, lies on a common radius line perpendicular to the axis 2, this lineforming the third axis. Parallel links 15 are pivoted to the pins 14,the other ends of the links 15 being connected to the chuck body 1 viajournal pins 16 which in turn, together with the axis 4, lie on a commonradius line extending perpendicularly to the axis 2. The effectivelength of the guides 15 thus corresponds to the length of the lever arms10 of the bell cranks 3. In this way a parallelogram linkage is producedwhich ensures that the clamping jaws are always guided exactly normal tothe axis of rotation 2 when an opening or closing movement of the bellcranks 3 takes place.

Locking bores 17 and 17' are provided in the chuck body 1 and on thebell cranks 3 respectively. For the purpose of locking one of the bellcranks 3 the pin connecting the guide shackles 8 and the short leverarms 9 of the bell cranks 3 can be withdrawn and inserted into the bores17 and 17. The piston 7 then moves only one hell crank 3 and theassociated clamping jaw 5. This enables workpieces which require aneccentric application from one side to be machined.

The bell cranks 3 are formed by twin arms receiving the clamping jaws 5between them. It is thus possible to lead the links 15 largely withinthe bell cranks 3. The axis 4 of the bell cranks 3 is formed by amassive pin which is untwistably guided in bearing bushes 18 in thechuck body 1.

A hydraulic control cylinder 19 for operating an actuating member 20(FIG. 3) is disposed inwardly of each clamping jaw 5 between the twinarms of each bell crank 3. The working and configuration of theseactuating members 20 can be seen in FIGS. 3 to 10.

In essence the actuating members 20 comprise a pin 21 connected to ajaw5 (not shown in FIG. 3) and carrying four equally spaced flanges. Theflanges are suitably formed by plunge-cutting annular grooves 23.Between any two juxtaposed flanges 22 are supported journal pins ofrollers 24. Two rollers 24, mutually offset by 180, are arranged in anygroove between any two adjacent flanges. As is shown by FIGS. 4, 6 and8, the rollers of any axially succeeding set of rollers are angularlyoffset relative to one another by 60.

The actuating member 20 rotatably journalled in the jaws 5 is actuatedvia the rollers 24 by pistons 25, 26 and 27 guided in the cylinder 19. Apiston rod 25', 26', 27', respectively is associated with each piston,the piston rods of the rearwardly located pistons 25 and 26 beingsealedly led through the pistons located ahead of them. Piston shoes 28,29 and 30 are so fixed to the free ends of the piston rods that theyform a right angle with thelongitudinal axis of the actuating member 20.

Contacts 31, 32 and 33 arranged on the piston shoes are diagrammaticallyindicated in FIGS. 4 to 10. These contacts cooperate with correspondingcountercontacts 31', 32 and 33' in the clamping jaws and serve to givean electric return signal whenever one of the piston shoes is inretaining contact with both of its associated rollers 24.

In FIGS. 3 to 10 the rollers have been labelled with Roman numerals I toIII for the purpose of differentiating between the individual indexingsteps, and additionally differentiation between the two rollers of eachset of rollers has been made by adding the indices a and b.

In the position of FIG. 3 the piston 25 is pressurized by introducingpressure medium into the cylinder chamber 34 and urges its piston shoe28 against the pair of rollers Ia and lb. This pair of rollers thusnecessarily stands at a right angle'to the direction of the pistonstroke.

According to FIG. 5 the cylinder chamber 35 associated with piston 27 ispressurized, so that the piston shoe 29 is thrust against both rollersIla and IIb after the actuating member 20 has been turned by Accordingto FIG. 7 the cylinder chamber 36 associated with piston 26 ispressurized. The piston shoe 30 is thereby thrust against roller Illauntil the piston shoe 30 is in retaining contact with both rollers Illaand Illb. Thus a further 60 rotation of the actuating member 20 isachieved.

FIGS. 9 and 10 illustrate that an intermediate pivotal position can beset by varying the diameter of roller la relative to that of roller lb.

In the foregoing discussion only two rollers are associated with eachpiston and each system of actuation surfaces or rollers. But of coursethree, four, six or more rollers per set of actuation surfaces can beprovided and thus any desired divisional or indexing angle can be set.With two rollers per system and three pistons in the cylinder 60rotation per step results. With three rollers per piston one obtains 40rotation per step. 30 rotation per step results with four rollers.Additionally, more than three pistons can be provided in the cylinder.When, for example, two rollers are then associated with each piston 45rotation per step will result.

Due to the above described design of the actuating member the pivot pinsof quadrangular or complex special profiles necessary in the knownswivel chucks become redundant. The actuating member 20 itself is a pureand simply produceable turned piece. At the same time, the pistonsactuating the actuating member are guided in a common cylinder. Thus itis no longer necessary to observe a precise angular association duringproduction. Additionally, any tolerances which may occur and which couldlead to lack of accuracy can be compensated for by appropriate choice ofroller diameters. Since the actuating member 20 and associated rollers24 are, as a rule, replaceable as a single unit, any correction oncemade need not be altered.

The pistons sequentially disposed in the common cylinder each requireonly one oil supply line. Pressurizing of one piston side necessarilyresults in the other pistons being led back from the rollers.

When a piston is placed under pressure the piston shoe of that pistonforces two of its associated rollers into a position perpendicular tothe piston stroke direction. Thus the actuating member is turned intothis position if it was not already in this position. For succeedingfurther rotation of the actuating member with the clamping jaw one ofthe other pistons is pressurized.

The sequence of pressurizing the pistons is optional and is suitablyprogramme controlled as required. Thus the sense of rotation of theactuating member is also optionally variable. If it is intended torotate the actuating member by only extremely small angles, e.g., lessthan l0, and if it becomes apparent that the thereby applied indexingmomentum is too small to overcome a certain resistance, then it ispossible to take into consideration in the programme control that afurther piston having a greater indexing momentum can be used 'to assistinitiation of the rotary movement, but the indexing is completed by thepiston determining the small angle of rotation.

In accordance with the illustration of FIG. 9 the actuating member mayat the same time be designed as an actuating drum. To this end grooves37 may be associated with control switches (not shown). The distributionof the grooves 37 on the circumference of the flanges 22 and theirrelative angular association on various flanges may be optionallyselected. In dependence on the rotational position, at any given time,of the actuating member 20 one or more of the grooves gives an indexinginstruction to the turning machine via the associated co ntrol'switches,whereby the processing associated with the rotational position inquestion is initiated. In this way it is possible to feed into themachine the finishing programme" of a workpiece together with the pivotaxis cut out for a specific workpiece.

FIGS. 11 to 13 illustrate diagrammatically the course of movementsduring the opening or closing displacement of the clamping jaws 5. TheFigures demonstrate that as a result of the arrangement of the guides 15the clamping jaws 5 are at all times led exactly perpendicular to theaxis of rotation 2.

I claim:

1. A swivel chuck comprising, in combination:-

a. a body adapted to be rotated about a first axis;

b. two arms each pivoted to said body about a second axis perpendicularto said first axis;

c. a jaw carried by each arm at a location spaced from its second axis,each said jaw being rotatable with respect to its associated arm about athird axis perpendicular to the first and second axes;

d. a cylinder carried by each of said'arms;

e. at least two pistons reciprocable within each of said cylinders;

f. an actuating member rotatable with each jaw; and

g. at least two sets of actuation surfaces on each actuating member,angularly offset with respect to one another about said third axis andpositioned to be acted upon by said pistons effective to cause rotationof said members and thereby of said jaws.

2. A swivel-chuckas claimed in claim 1, wherein said actuating membercomprises annular grooves, spaced along said third axis, and whereinsaid actuating surfaces each comprises two rollers mounted in one ofsaid grooves so as to be rotatable about axes parallel to said thirdaxis.

3. A swivel chuck as claimed in claim 2, wherein said rollers areexchangeable.

4. A swivel chuck as claimed in claim 2, wherein said actuating membersis exchangeable.

5. A swivel chuck as claimed in claim 2, and further comprising meansdefining a plurality of axial bores associated with each groove, wherebythe angular positions of the rollers can be varied.

6. A swivel chuck as claimed in claim2', wherein said actuating memberincludes three annular grooves, each groove being provided with tworollers offset by with respect to one another, the rollers of one groovebeing offset by 60 with respect to the rollers of the other two grooves.

7. A swivel chuck as claimed in claim 2, and further comprising pistonshoes associated with each piston and adapted to abut the rollers, andswitching contacts on the piston shoes and on the rollers, said contactsbeing arranged in a control circuit which is thereby closed when apiston shoe abuts both rollers of an annular groove.

8. A swivel chuck comprising, in combination:

a. a body adapted to be rotated about a first axis;

b. two bell cranks each pivoted to said body about a second axisperpendicular to said first axis;

c. a jaw carried by each bell crank at a location spaced from its secondaxis, each of said jaw being rotatable with respect to its associatedbell crank about a third axis perpendicular to the first and secondaxes;

d. means for rotating said jaws about said third axis;

e. a link associated with each bell crank and pivoted to said body andthe associated jaw, the effective length of said link being equal to thedistance between the third axis and the second axis of that bell crank,effective to provide a parallelogram linkage to support said jaw for aconstant angular position during pivoting of the bell crank; and

f. means acting parallel to said first axis to pivot said bell cranksabout said second axes.

9. A swivel chuck as claimed in claim 8, wherein the bell-cranks eachcomprise a first arm pivoted to one of said jaws and a second armconnected to said pivoting means, said second arms being shorter thansaid first arms.

10. A swivel chuck as claimed in claim 9, wherein said bell cranks eachcomprise two members spaced apart axially, with respect to said secondaxes, and wherein said jaws and said rotating means are located betweensaid members.

1. A swivel chuck comprising, in combination:a. a body adapted to berotated about a first axis; b. two arms each pivoted to said body abouta second axis perpendicular to said first axis; c. a jaw carried by eacharm at a location spaced from its second axis, each said jaw beingrotatable with respect to its associated arm about a third axisperpendicular to the first and second axes; d. a cylinder carried byeach of said arms; e. at least two pistons reciprocable within each ofsaid cylinders; f. an actuating member rotatable with each jaw; and g.at least two sets of actuation surfaces on each actuating member,angularly offset with respect to one another about said third axis andpositioned to be acted upon by said pistons effective to cause rotationof said members and thereby of said jaws.
 2. A swivel-chuck as claimedin claim 1, wherein said actuating member comprises annular grooves,spaced along said third axis, and wherein said actuating surfaces eachcomprises two rollers mounted in one of said grooves so as to berotatable about axes parallel to said third axis.
 3. A swivel chuck asclaimed in claim 2, wherein said rollers are exchangeable.
 4. A swivelchuck as claimed in claim 2, wherein said actuating members isexchangeable.
 5. A swivel chuck as claimed in claim 2, and furthercomprising means defining a plurality of axial bores associated witheach groove, whereby the angular positions of the rollers can be varied.6. A swivel chuck as claimed in claim 2, wherein said actuating memberincludes three annular grooves, each groove being provided with tworollers offset by 180* with respect to one another, the rollers of onegroove being offset by 60* with respect to the rollers of the other twogrooves.
 7. A swivel chuck as claimed in claim 2, and further comprisingpiston shoes associated with each piston and adapted to abut therollers, and switching contacts on the piston shoes and on the rollers,said contacts being arranged in a control circuit which is therebyclosed when a piston shoe abuts both rollers of an annular groove.
 8. Aswivel chuck comprising, in combination: a. a body adapted to be rotatedabout a first axis; b. two bell cranks each pivoted to said body about asecond axis perpendicular to said first axis; c. a jaw carried by eachbell crank at a location spaced from its second axis, each of said jawbeing rotatable with respect to its associated bell crank about a thirdaxis perpendicular to the first and second axes; d. means for rotatingsaid jaws about said third axis; e. a link associated with each bellcrank and pivoted to said body and the associated jaw, the effectivelength of said link being equal to the distance between the third axisand the second axis of that bell crank, Effective to provide aparallelogram linkage to support said jaw for a constant angularposition during pivoting of the bell crank; and f. means acting parallelto said first axis to pivot said bell cranks about said second axes. 9.A swivel chuck as claimed in claim 8, wherein the bell cranks eachcomprise a first arm pivoted to one of said jaws and a second armconnected to said pivoting means, said second arms being shorter thansaid first arms.
 10. A swivel chuck as claimed in claim 9, wherein saidbell cranks each comprise two members spaced apart axially, with respectto said second axes, and wherein said jaws and said rotating means arelocated between said members.